Objective: To characterize differences in interval timing between patients with Parkinson’s disease and Dementia with Lewy bodies (DLB) and evaluate their relationship to cognitive fluctuations in DLB.

Background: Alterations in time perception have been demonstrated in patients with Parkinson’s disease (PD) and has been linked to dopaminergic deficiency. However, administration of cholinergic medications in healthy subjects have also been shown to influence time perception. Cholinergic deficiency is pathologically characteristic of Dementia with Lewy bodies (DLB) and is thought to be related to cognitive fluctuations. We hypothesized that time perception would be differentially altered between patients with PD and DLB compared to controls and that qualities of interval timing may relate intrinsically to cognitive fluctuations in DLB.

Method: 25 patients with DLB, 13 age-matched PD off dopaminergic medication and 16 age-matched older controls underwent testing using a simple time perception paradigm probing different aspects of interval timing including time estimation, production and pacing. Intervals ranging from 10 to 90 seconds were randomized between groups. Fluctuations in DLB patients was measured using the clinician assessment of fluctuation (CAF) and one-day fluctuation (OFS) scales respectively.

Results: We found significant group differences in interval timing for time estimation (U=13.5, p<0.001) and time production (U=14.4, p<0.001) but not time pacing. These effects were most pronounced at the longest interval of 90s. DLB patients estimated less time compared to controls (p=0.04) and PD (p<0.001), whilst PD estimated more time than controls and DLB (p=0.04). Meanwhile both PD (p=0.003) and DLB (p<0.001) produced less time relative to controls. Absolute deviation in time estimation at 90 seconds correlated with fluctuation presence (CAF; r=0.47;p=0.009) whilst errors in time pacing at 90s correlated with fluctuation severity (OFS; rs=0.65, p<0.001). Receiver operating characteristic analysis identified time production at 90 seconds to be an accurate measure for distinguishing controls from PD/DLB (AUC=0.87).

Conclusion: Temporal processing is differentially altered between PD and DLB likely reflecting different neurotransmitter dependencies. Altered interval timing may be an objective marker of fluctuations in the clinical setting and potential discriminator in prodromal states.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/differential-temporal-processing-across-lewy-body-disorders-and-relation-to-cognitive-fluctuations/